CALGARY, July 13 (Reuters) - Syncrude Canada on Friday told buyers it would cut crude deliveries in August by about 35 percent after an outage last month at its oil sands site in northern Alberta, two market sources familiar with the matter said.

Suncor Energy Inc, the biggest stakeholder in the northern Alberta project, said earlier this week the site will resume some operations in July and reach full production in September.

A Suncor spokeswoman did not immediately respond to a request for comment.

The cut in deliveries was first reported by Bloomberg. (Reporting by Devika Krishna Kumar and Rod Nickel in Calgary, Alberta; editing by Grant McCool)